The present invention relates generally to thermocouples and more particularly to multipoint thermocouple assemblies.
Multipoint thermocouple assemblies have been used in the past, for example, to obtain information concerning the temperature occurring at different depths or heights in a utilization environment, such as a cracking tower or other process vessel, or the like. Such multipoint thermocouple assemblies may have a length from a few feet to in excess of 100 feet and are inserted into such process vessel.
A typical prior thermocouple assembly includes several thermocouples, each having its measuring junction at a different location along the length of the assembly, and some means is provided to bundle together the thermocouples and to direct their terminating ends to a common junction box for effecting electrical connections to measuring equipment. Usually the measuring junctions and portions of the leads of the thermocouples are contained in a protective tube well that effects such bundling and isolates the thermocouples from the external ambient environment, which may contain corrosives or other material that may affect the thermocouple, for example. Ideally the measuring junctions are held in thermal energy transfer contact with the inside wall of such a protective tube well, and such well preferably is of good thermally conductive material so that the thermocouple measuring junctions essentially sense the temperature directly outside of the wall portion of the protective tube well with which they are in contact.
In such typical prior multipoint thermocouple assemblies the thermocouples are fixed in the assembly, i.e. they are securely attached to a support within the well or to the wall of the well by permanent means. As a result, individual thermocouples cannot be removed individually for examination, testing, and/or replacement. Rather, in order to repair or to replace only a single thermocouple in a multipoint thermocouple assembly, it has been necessary in the past to remove the entire multipoint thermocouple assembly from the process vessel, for example. While such assembly is removed from the process vessel, the temperature sensing data ordinarily provided thereby is lost until it or a substitute thermocouple assembly has been inserted back into the process vessel.